Why is my 1982 Chevy Van G30 bogging down? Now it won't move at all.

Do you have a brake problem... Staying applied all the time.... OR a transmission problem.... Slipping??

Exhaust sound a little different? Vissualy inspect converters for signs of severe overheating , or run it at night get it to act up , and then while it's running (in park) look underneath for orange cats. (NOT Tabbys).